1. Field of the Invention
The present invention relates to an alarm driving signal generator for generating a signal to drive a voltage actuated alarm device such as electronic chime (piezoelectric buzzer) in response to an alarm signal.
2. Description of the Prior Art
As alarm sound producing devices, recently electronic chimes such as piezoelectric buzzers have been widely used. The piezoelectric buzzer can be actuated by voltage without passing drive current therethrough. Further, since the resonant frequency of a piezoelectric element is relatively high, a high frequency driving (voltage) signal (clock) is applied to the element to produce alarm sound. On the other hand, the buzzer is usually driven intermittently to produce a warning sound. Therefore, the high frequency driving signal is usually amplitude modulated by a low-frequency signal obtained by a CR circuit.
In the conventional alarm driving signal generator as described above, the circuit configuration is relatively complicated, and therefore there exists a problem in that the number of parts is large and the cost is high.
A more detailed description of the prior-art-alarm driving signal generator will be made with reference to the attached drawings under DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.